This application is related to and claims the priority of Japanese Patent Application No. 2000-127,183, which was filed on Apr. 27, 2000, the entire contents of which is hereby expressly incorporated by reference.
1. Field of the Invention
The present invention generally relates mounting arrangements for rear axles of land vehicles. More particularly, the present invention relates to such mounting arrangements in three or four wheel vehicles, such as all terrain vehicles (ATVs).
2. Description of the Related Art
Recreational all terrain vehicles generally comprise a frame that is carried by at least one front wheel and a pair of rear wheels. The rear wheels typically are attached to the frame with a swing arm, which is connected to a rear portion of the frame and which is capable of pivotal movement relative to the frame about a generally horizontal axis. A shock absorber often is disposed between the swing arm and the frame to control movement of the swing arm during operation of the vehicle over rough terrain.
One example of such a swing arm was disclosed in Japanese Patent No. 2535328. FIG. 1 reproduces FIG. 1 of that patent. As illustrated, the swing ann 10 generally comprises an elongated neck portion 12 and a bearing carrying portion 14. A forward end of the elongate neck portion 12 comprises a pivot shaft 16 and a bearing configuration 18 to promote pivotal movement of the swing arm 10 relative to the frame to which the swing arm 10 is attached. A flange 20 is provided along the neck portion 12. The flange 20 provides a connecting location for a shock absorber or damper.
The bearing carrying portion 14 is connected to the rear end of the neck portion 12. In the illustrated arrangement, the bearing carrying portion 14 is comprised of a square tube 22. The square tube 22 generally is welded directly to the neck portion 12 and provides a housing in which an axle 24 of the vehicle is mounted.
Two sets of bearings 26 positioned within a housing having an upper block 28 and a lower block 30 are disposed within the tube 22. A set of four threaded fasteners 32, two of which are shown, are used to secure the housing in position within the tube 22. The threaded fasteners extend through longitudinal slots 34 formed in the top and bottom surfaces of the square tube 22. Thus, the longitudinal position of the axle 24 can be adjusted forward and backward.
A further threaded fastener 36 extends rearward from the rear of the housing and through the square tube. This threaded fastener 36 receives nuts 38 that can be tightened to pull the axle 24 rearward through the bearing carrying portion 14 such that tension is increased to a chain used to drive the rear axle 24.
One drawback to this swing arm construction is that the lateral ends of the square tube are not enclosed. Thus, dust, dirt and other debris can easily become lodged in the tube. Not only does this detract from an otherwise clean vehicle, but the dirt can hamper maintenance and increase wear. For instance, if the chain needs to be slacked, then the dirt must be cleared sufficiently from within the tube to allow the bearings and the associated housing to be moved forward within the tube.
Another drawback to this swing arm construction relates to providing tension to the chain. As can be appreciated, the size of the threaded fastener 36 must be fairly substantial to withstand the loads applied when tensioning the chain. At least two conditions necessitate the increased size. First, only a single member is used to apply the initial tension. Second, the single member is receiving a tensile load under most conditions even though the other threaded fasteners are tightened into position.
Accordingly, an improved swing arm construction is desired whereby the above-noted drawbacks can be overcome. In addition, the improved construction preferably provides simpler manufacture as well as maintenance.
Accordingly, one aspect of the present invention involves a recreational all terrain vehicle comprising a frame assembly with an engine disposed within the frame assembly. The engine is adapted to power an output shaft and a drive pulley is secured to the output shaft. A swing arm is pivotally connected to the frame assembly with a pair of rear wheels being supported by the swing arm. A pivot axis is defined at a location in which the swing arm is pivotally connected to the frame assembly. The swing arm comprises a forward neck portion and a rearward bearing carrying portion. An axle is connected to the pair of rear wheels with the axle being adapted to rotate about an axle rotational axis. The pivot axis and the axle rotational axis are generally parallel. A driven pulley is connected to the axle with a flexible transmitter extending around the drive pulley and the driven pulley. The bearing carrying portion comprises an outer housing secured to the neck portion. The axle extends through a transverse opening extending through a portion of the outer housing. A pair of plates are positioned on lateral sides of the outer housing and at least partially close the transverse opening. A tubular member extends through the transverse opening and is connected to the pair of plates. A first fastener and a second fastener transversely extend between the pair of plates while the first fastener and the second fastener are adapted to secure the pair of plates to the outer housing.
Another aspect of the present invention involves a swing arm for a recreational all terrain vehicle. The swing arm comprises a neck portion and a bearing carrier portion. The neck portion extends partway into the bearing carrier portion and is secured to the bearing carrier portion. The bearing carrier portion comprises an outer housing with the outer housing defining a transverse opening. A first slot and a second slot also extend transversely through the outer housing and are generally parallel to the transverse opening. A first plate is attached to a first lateral side of the outer housing and a second plate is attached to a second lateral side of the outer housing. A first elongated member extends through the first slot and a second elongated member extends through the second slot. The first plate and the second plate substantially cover the transverse opening and are secured to the outer housing by the first elongated member and the second elongated member.
A further aspect of the present invention involves a recreational all terrain vehicle comprising a frame assembly with an engine disposed within the frame assembly. The engine is adapted to power an output shaft with a drive pulley being secured to the output shaft. A swing arm is pivotally connected to the frame assembly. A pair of rear wheels are supported by the swing arm and a pivot axis is defined at a location in which the swing arm is pivotally connected to the frame assembly. The swing arm comprises a forward neck portion and a rearward bearing carrying portion. An axle is connected to the pair of rear wheels with the axle being adapted to rotate about an axle rotational axis. The pivot axis and the axle rotational axis are generally parallel. A driven pulley is connected to the axle with a flexible transmitter extending around the drive pulley and the driven pulley. The neck portion extends partway into the bearing carrying portion and is secured to the bearing carrier portion. The bearing carrying portion comprises an outer housing that defines a transverse opening. A first slot and a second slot also extend transversely through the outer housing and are generally parallel to the transverse opening. The axle extends through the transverse opening. A pair of plates are positioned on opposing lateral sides of the outer housing. A first elongated member and a second elongated member extend through the first slot and the second slot respectively and the pair of plates substantially cover the transverse opening. The pair of plates are secured to the outer housing by the first elongated member and the second elongated member.
For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.